1. Field of the Invention
The present invention relates to multiple location dimming systems having multiple smart dimmers, for example, a three-way dimming system that includes smart dimmer switches at both locations of the three-way system. In particular, all of the smart dimmers in the multiple location dimming system according to the present invention are operable to carry the same load current to control one or more lighting loads in unison and to display a present intensity level of the lighting load(s) on a status indicator.
2. Description of the Related Art
Three-way and four-way switch systems for use in controlling loads in buildings, such as lighting loads, are known in the art. Typically, the switches used in these systems are wired to the building's alternating-current (AC) wiring system, are subjected to AC source voltage, and carry full load current, as opposed to low-voltage switch systems that operate at low voltage and low current, and communicate digital commands (usually low-voltage logic levels) to a remote controller that controls the level of AC power delivered to the load in response to the commands. Thus, as used herein, the terms “three-way switch”, “three-way system”, “four-way switch”, and “four-way system” mean such switches and systems that are subjected to the AC source voltage and carry the full load current.
A three-way switch derives its name from the fact that it has three terminals and is more commonly known as a single-pole double-throw (SPDT) switch, but will be referred to herein as a “three-way switch”. Note that in some countries a three-way switch as described above is known as a “two-way switch”.
A four-way switch is a double-pole double-throw (DPDT) switch that is wired internally for polarity-reversal applications. A four-way switch is commonly called an intermediate switch, but will be referred to herein as a “four-way switch”.
In a typical, prior art three-way switch system, two three-way switches control a single load, and each switch is fully operable to independently control the load, irrespective of the status of the other switch. In such a system, one three-way switch must be wired at the AC source side of the system (sometimes called “line side”), and the other three-way switch must be wired at the load side of the system.
FIG. 1A shows a standard three-way switch system 100, which includes two three-way switches 102, 104. The switches 102, 104 are connected between an AC voltage source 106 and a lighting load 108. The three-way switches 102, 104 each include “movable” (or common) contacts, which are electrically connected to the AC voltage source 106 and the lighting load 108, respectively. The three-way switches 102, 104 also each include two fixed contacts. When the movable contacts are making contact with the upper fixed contacts, the three-way switches 102, 104 are in position A in FIG. 1A. When the movable contacts are making contact with the lower fixed contact, the three-way switches 102, 104 are in position B. When the three-way switches 102, 104 are both in position A (or both in position B), the circuit of system 100 is complete and the lighting load 108 is energized. When switch 102 is in position A and switch 104 is in position B (or vice versa), the circuit is not complete and the lighting load 108 is not energized.
Three-way dimmer switches that replace three-way switches are known in the art. An example of a three-way dimmer switch system 150, including one prior art three-way dimmer switch 152 and one three-way switch 104 is shown in FIG. 1B. The three-way dimmer switch 152 includes a dimmer circuit 152A and a three-way switch 152B. A typical, AC phase-control dimmer circuit 152A regulates the amount of energy supplied to the lighting load 108 by conducting for some portion of each half-cycle of the AC waveform, and not conducting for the remainder of the half-cycle. Because the dimmer circuit 152A is in series with the lighting load 108, the longer the dimmer circuit conducts, the more energy will be delivered to the lighting load 108. Where the lighting load 108 is a lamp, the more energy that is delivered to the lighting load 108, the greater the light intensity level of the lamp. In a typical dimming operation, a user may adjust a control to set the light intensity level of the lamp to a desired light intensity level. The portion of each half-cycle for which the dimmer conducts is based on the selected light intensity level. The user is able to dim and toggle the lighting load 108 from the three-way dimmer switch 152 and is only able to toggle the lighting load from the three-way switch 104. Since two dimmer circuits cannot be wired in series, the three-way dimmer switch system 150 can only include one three-way dimmer switch 152, which can be located on either the line side or the load side of the system.
A four-way switch system is required when there are more than two switch locations from which to control the load. For example, a four-way system requires two three-way switches and one four-way switch, wired in well known fashion, so as to render each switch fully operable to independently control the load irrespective of the status of any other switches in the system. In the four-way system, the four-way switch is required to be wired between the two three-way switches in order for all switches to operate independently, i.e., one three-way switch must be wired at the AC source side of the system, the other three-way switch must be wired at the load side of the system, and the four-way switch must be electrically situated between the two three-way switches.
FIG. 1C shows a prior art four-way switching system 180. The system 180 includes two three-way switches 102, 104 and a four-way switch 185. The four-way switch 185 has two states. In the first state, node A1 is connected to node A2 and node B1 is connected to node B2. When the four-way switch 185 is toggled, the switch changes to the second state in which the paths are now crossed (i.e., node A1 is connected to node B2 and node B1 is connected to node A2). Note that a four-way switch can function as a three-way switch if one terminal is simply not connected.
FIG. 1D shows another prior art switching system 190 containing a plurality of four-way switches 185. As shown, any number of four-way switches can be included between the three-way switches 102, 104 to enable multiple location control of the lighting load 108.
Multiple location dimming systems employing a smart dimmer switch and a specially designed remote (or “accessory”) switch that permit the dimming level to be adjusted from multiple locations have been developed. A smart dimmer is one that includes a microcontroller or other processing means for providing an advanced set of control features and feedback options to the end user. For example, the advanced features of a smart dimmer may include a protected or locked lighting preset, fading, and double-tap to full intensity. To power the microcontroller, smart dimmers include power supplies, which draw a small amount of current through the lighting load each half-cycle when the semiconductor switch is non-conducting. The power supply typically uses this small amount of current to charge a storage capacitor and develop a direct-current (DC) voltage to power the microcontroller. An example of a multiple location lighting control system, including a wall-mountable smart dimmer switch and wall-mountable remote switches for wiring at all locations of a multiple location dimming system, is disclosed in commonly assigned U.S. Pat. No. 5,248,919, issued on Sep. 28, 1993, entitled LIGHTING CONTROL DEVICE, which is herein incorporated by reference in its entirety.
Referring again to the system 150 of FIG. 1B, since no load current flows through the dimmer circuit 152A of the three-way dimmer switch 152 when the circuit between the supply 106 and the lighting load 108 is broken by either three-way switch 152B or 104, the dimmer switch 152 is not able to include a power supply and a microcontroller. Thus, the dimmer switch 152 is not able to provide the advanced set of features of a smart dimmer to the end user.
FIG. 2 shows an example multiple location lighting control system 200 including one wall-mountable smart dimmer switch 202 and one wall-mountable remote switch 204. The dimmer switch 202 has a Hot (H) terminal for receipt of an AC source voltage provided by an AC power supply 206, and a Dimmed Hot (DH) terminal for providing a dimmed-hot (or phase-controlled) voltage to a lighting load 208. The remote switch 204 is connected in series with the DH terminal of the dimmer switch 202 and the lighting load 208, and passes the dimmed-hot voltage through to the lighting load 208.
The dimmer switch 202 and the remote switch 204 both have actuators to allow for raising, lowering, and toggling on/off the light intensity level of the lighting load 208. The dimmer switch 202 is responsive to actuation of any of these actuators to alter the dimming level (or power the lighting load 208 on/off) accordingly. In particular, actuation of an actuator at the remote switch 204 causes an AC control signal, or partially rectified AC control signal, to be communicated from that remote switch 204 to the dimmer switch 202 over the wiring between the Accessory Dimmer (AD) terminal of the remote switch 204 and the AD terminal of the dimmer switch 202. The dimmer switch 202 is responsive to receipt of the control signal to alter the dimming level or toggle the load 208 on/off. Thus, the load can be fully controlled from the remote switch 204.
The user interface of the dimmer switch 202 of the multiple location lighting control system 200 is shown in FIG. 3. As shown, the dimmer switch 202 may include a faceplate 310, a bezel 312, an intensity selection actuator 314 for selecting a desired level of light intensity of a lighting load 208 controlled by the dimmer switch 202, and a control switch actuator 316. The faceplate 310 need not be limited to any specific form, and is preferably of a type adapted to be mounted to a conventional wall-box commonly used in the installation of lighting control devices. Likewise, the bezel 312 and the actuators 314, 316 are not limited to any specific form, and may be of any suitable design that permits manual actuation by a user.
An actuation of the upper portion 314A of the actuator 314 increases or raises the light intensity of the lighting load 208, while an actuation of the lower portion 314B of the actuator 314 decreases or lowers the light intensity. The actuator 314 may control a rocker switch, two separate push switches, or the like. The actuator 316 may control a push switch, though the actuator 316 may be a touch-sensitive membrane. The actuators 314, 316 may be linked to the corresponding switches in any convenient manner. The switches controlled by actuators 314, 316 may be directly wired into the control circuitry to be described below, or may be linked by an extended wired link, infrared (IR) link, radio frequency (RF) link, power line carrier (PLC) link, or otherwise to the control circuitry.
The dimmer switch 202 may also include an intensity level indicator in the form of a plurality of light sources 318, such as light-emitting diodes (LEDs). Light sources 318 may be arranged in an array (such as a linear array as shown) representative of a range of light intensity levels of the lighting load 208 being controlled. The intensity levels of the lighting load 208 may range from a minimum intensity level, which is preferably the lowest visible intensity, but which may be “full off”, or zero, to a maximum intensity level, which is typically “full on”, or substantially 100%. Light intensity level is typically expressed as a percent of full intensity. Thus, when the lighting load 208 is on, light intensity level may range from 1% to substantially 100%.
The system shown in FIG. 2 provides a fully functional three-way switching system wherein the user is able to access all functions, such as, for example, dimming at both locations. However, in order to provide this functionality, both switching devices need to be replaced with the respective devices 202, 204. Further, since the remote switch 204 does not have LEDs, no feedback can be provided to a user at the remote switch 204.
Sometimes it is desired to place only one smart switch in the three-way or four-way switching circuit. As shown in FIG. 1B, it is not possible heretofore to do this by simply replacing the dimmer 152 with a smart dimmer, leaving mechanical three-way switch 104 in the circuit because when switch 104 breaks the circuit, power no longer is provided to the microcontroller of the smart dimmer (in place of the dimmer 152) because current no longer flows through the dimmer to the lighting load 108. The three-way and four-way dimmer switch according to the present invention provides a solution to this problem and also optionally provides a means for remote control of the switch.
In one prior art remote control lighting control system, a single multi-location dimmer and up to nine “accessory” dimmers can be installed on the same circuit to enable dimming from a plurality of controls. In the prior art, accessory dimmers are necessary because prior art multi-location dimmers are incompatible with mechanical three-way switches. Accessory dimmers installed throughout a house can greatly increase the cost of the components and of the installation of a dimming system.
Moreover, even though the multiple location lighting control system 200 allows for the use of a smart dimmer switch in a three-way system, it is necessary for the customer to purchase the remote switch 204 along with the smart dimmer switch 202. Often, the typical customer is unaware that a remote switch is required when buying a smart dimmer switch for a three-way or four-way system until after the time of purchase when the smart dimmer switch is installed and it is discovered that the smart dimmer switch will not work properly with the existing mechanical three-way or four-way switch. Therefore, there exists a need for a smart dimmer that may be installed in any location of a three-way or four-way system without the need to purchase and install a special remote switch.
Smart dimmers that are operable to be installed in a three-way system in place of one of the three-way switches are known. FIG. 4A shows a prior art three-way system 400 having a smart three-way dimmer 402 and FIG. 4B shows a prior art three-way system 450 having a smart three-way dimmer 452. The smart three-way dimmers 402, 452 are described in greater detail in co-pending, commonly-assigned U.S. patent application Ser. No. 11/447,496, filed Jun. 6, 2006, entitled DIMMER SWITCH FOR USE WITH LIGHTING CIRCUITS HAVING THREE-WAY SWITCHES, the entire disclosure of which is hereby incorporated by reference in its entirety. Note that the dimmers 402, 452 may be coupled on either the line-side or the load-side of the three-way systems 400, 452.
The smart dimmer 402 comprises a first dimmer circuit 410 coupled between an AC source 406 and the first fixed contact A of a standard three-way switch 404 and a second dimmer circuit 412 coupled between the AC source and the second fixed contact B of the three-way switch 404. The movable contact of the three-way switch 404 is coupled to a lighting load 408. The smart dimmer comprises a control circuit 414 coupled across the dimming circuits 410, 412 via two diodes 416. The control circuit 414 comprises a power supply, which is operable to charge through the lighting load 408 via one of the diodes 416 depending upon the position of the movable contact of the three-way switch 404. Preferably, the control circuit is operable to determine whether the three-way switch 404 is in position A or position B depending upon whether a voltage is developed across the first dimmer circuit 410 or the second dimmer circuit 412, respectively. The smart three-way dimmer 402 is operable to provide feedback to a user of the intensity of the lighting load 408.
The smart dimmer 452 only comprises a single dimmer circuit 460 coupled between the AC source 406 and the first fixed contact A of the three-way switch 404. The smart dimmer also comprises a control circuit 464 coupled across the dimmer circuit 462 and a current sense circuit 468 coupled between the first fixed contact A and the second fixed contact B of the three-way switch 404. The control circuit 462 includes a power supply that is operable to charge through lighting load 408. The control circuit 464 is operable to determine whether the three-way switch 404 is in position A or position B in response to a control signal generated by the current sense circuit 468. The control signal is provided to the control circuit 464 when the current sense circuit 468 senses the charging current of the power supply flowing through the second fixed contact B of the three-way switch 404. The smart three-way dimmer 452 is operable to provide feedback to a user of the intensity of the lighting load 408.
However, the three-way systems 400, 450 cannot include more than one smart dimmer 402, 452. Therefore, there is a need for a three-way system that is operable to include a smart dimmer at both locations of the three-way system. Further, there is a need for a multiple location dimming system having identical dimmers that wire in each location of the dimming system and that each have status indicators.